The “Transformers” movies, at least the first batch, don’t really see the titular characters as, well, characters. No, they’re just talking props to facilitate the action and product placement for General Motors. Only Optimus Prime (Peter Cullen) and Bumblebee are ever afforded more than five minutes of screentime and a hint of personality.
Tellingly, the Transformers originally weren’t going to speak at all in the 2007 movie. Orci and Kurtzman nixed that idea but its presence is still felt; Bumblebee “talks” via edited radio transmissions while the Decepticons mostly communicate with an unintelligible alien language.
In the first film, dividing the focus like this does make some sense; the story was an introduction to an alien world. Keeping “Transformers” grounded in the familiar and offering audiences only a taste was the natural way to go. However, the sequels never changed gears. 2009’s “Revenge of the Fallen” again makes Sam’s coming of age into the spine of the story, straining to keep him involved when his role ended after the first film. Since these are Michael Bay movies, the military continues to be the heroes of the action scenes, not the Autobots.
In general, I’d say “Transformers” does need a human element. They’re robots in disguise — what’s the point of them transforming into cars and jets without humans around them? Plus, if a film only had the robots, then it’s not live-action. The upcoming prequel, “Transformers: One,” will be set entirely on the robots’ homeworld Cybertron and, tellingly, is going to be full-on animated.